/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package facebook;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.restfb.json.JsonObject;
import javax.servlet.http.HttpSession;

@WebServlet(name = "WelcomeServlet", urlPatterns = {"/WelcomeServlet"})
public class WelcomeServlet extends HttpServlet {

    /** 
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        
        HttpSession session = request.getSession();
        try {
            String baseURL = Utilities.getBaseUrl(request);
            String  authURL = baseURL + "/fbapp/OAuthFilter",
                    signedRequest = request.getParameter("signed_request"); //from facebook
            
            if(signedRequest == null){ //if this page is called outside facebook
                out.println("You are a stupid, a computer scientist or both!");
                Thread.sleep(3000);                
                response.sendRedirect(Utilities.getBaseUrl(request));
            }
            else {
                
                String decodedPayload = Utilities.decodePayload(signedRequest, session);
                
                
                JsonObject user = new JsonObject(decodedPayload);
                String userID = Utilities.tryGetJsonKey(user, "user_id");

                if(userID == null){ //new user
                    Utilities.csrfProtection(session);
                 
                    out.println("<script> top.location.href='" + authURL +"'</script>");
                }
                else { // existing user
                    out.println("<br />");
                    out.println("<br />");
                    out.println("The Delo-Project is under development, but will be available soon!");
                    out.println("<br />");
                }
            }
        } 
        //Non invocare out.close() se la servlet viene richiamata nella jsp!!!
        catch (Exception e) {
            System.out.println(e);
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** 
     * Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Returns a short description of the servlet.
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}
